The present invention relates to hair treatment products for protecting hair against damage on heat drying, against environmental influences and hair treatments as well as for protecting other components of said hair treatment products against oxidation and degradation.
Antioxidants are essential substances in nature. They are used in cosmetics for protecting the compounds of said cosmetics and for protecting the skin against oxidative stress.
Oxidative stress is caused by ROS (Reactive Oxygen Species—reactive oxygen molecules). ROS are formed above all in water, since water is always saturated with oxygen.
Frequently, in cosmetics only oil soluble antioxidants are used, since quite a number of suitable substances are available, such as 3-tert.-butyl-4-hydroxyanisole or alpha-tocopherol.
However, the use of water soluble antioxidants is limited, since no suitable substances are available on the market.
Vitamin C (ascorbic acid) is a water soluble antioxidant, which is widespread in nature but is rarely used in cosmetics, since it is very unstable.
Oligomeric procyanidins, isolated from grape seeds or other plant parts, are very good antioxidants, which are useful in cosmetics. Procyanidins are polyphenols on the basis of catechin and epicatechin.
Thus, the publication U.S. Pat. No. 5,648,377 discloses the use of oligomeric procyanidins in combination with carotinoids for combating radicals in foodstuffs, foodstuff complements, cosmetic and pharmaceutical preparations.
However, the use of oligomeric procyanidins is not unproblematic, since said compounds are only conditionally stable if dissolved in water. Therefore, so far the use of such oligomeric procyanidins was essentially limited to dry products such as capsules or tablets as foodstuff complements.
The publication EP-A1-1,086,693 discloses the stabilization of proanthocyanidins in various products, such as tablets, foodstuffs and cosmetics by means of vitamin B6. The disclosed proanthocyanidins are principally dimers, in contrast to the present invention which is mainly directed to the use of oligomers. Furthermore, vitamin B6 is a water soluble vitamin. The use of grape seed extract and vitamin B6 in cosmetics, such as shampoos, in said publication is exclusively made for stabilizing the proanthocyanidins. Protection of hair by combining procyanidins with pure tocopherol cannot be deduced therefrom, just as little as the affinity of such a combination to hair. The example of a hair tonic comprising vitamin E acetate does not give any protection to the hair, since vitamin E acetate does not have sufficient antioxidant activity. However, vitamin E acetate can be cleaved in the skin to form pure tocopherol which then shows certain activities for promoting hair growth.
The publication EP-A1-0,768,079 discloses the use of dimeric proanthocyanidins for promoting hair growth. Whereas the described product additionally comprises free tocopherol, the publication does not disclose nor let deduce affinity of the product to hair, and thus does not disclose any protection of hair against radicals; which is not the purpose of said publication either.